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3 Part 3. Topic «Simple Machines»

3. 1 Warm-ups

3.1.1 Answer the following questions

a) What do you know about simple machines? What are their principles and uses?

b) Can you give any examples of simple machines?

3.1.2 Read the definition

“A simple machine is a device for altering the magnitude or direction of a force. The six basic types are the lever, screw, wheel and axle, pulley, wedge, inclined plane.”

lever - рычаг

wheel and axle – колесо и ось

pulley - блок

wedge - клин

inclined plane – наклонная плоскость

screw - винт

3.1.3 Do you know what these words mean? If you are not sure look them up in a dictionary

nail clipper, shovel, nutcracker, seesaw, crow-bar, elbow, tweezers, bottle opener, slide, stairs, ramp, escalator, slope, doorknob, pencil sharpener, bike, curtain rod, tow truck, mini-blind, flag pole, crane

3.1.4 Say what you think about the following statements

Simple machines are "simple" because most have only one moving part.

Machines do not reduce the amount of work for us, but they can make it easier.

"Work" is only done when something is moved.

"Work" is the product of effort and distance.

3.1.5 Optional writing activity. Write an essay or a paragraph describing three simple machines you can find in an office or classroom

3.1.6 Read for information

Vocabulary box

What is a Simple Machine?

Work is performed by applying a force over a distance. These simple machines create a greater output force than the input force; the ratio of these forces is the mechanical advantage of the machine. All six of the simple machines have been used for thousands of years, and the physics behind several of them were quantified by Archimedes. These machines can be used together to create even greater mechanical advantage, as in the case of a bicycle.

Background of inventions

Before engines and motors were invented, people had to do things like lifting heavy loads by hand. Using an animal could help, but what they really needed is some clever ways to either make work easier or faster. Ancient people invented, simple machines that would help them overcome resistive forces and allow them to do the desired work against those forces.

Ancient Egyptians

The ancient Egyptians, for example, used such inventions to help them build the pyramids. They used levers to pick up large blocks of stone. They put those blocks on rollers to move from one area to another. Then they used ramps to move the blocks up to the top of the pyramid they were building.

Ancient Romans

The ancient Romans used catapults to throw stones at their enemies. The catapult was a large lever. They used a pulley to pull down the arm of the catapult. The device was set on wheels--an advanced version of rollers--to move it from place to place.

Today

We still use those simple machines today, by themselves and as part of more complex machines.

3.2 Read the text quickly

Text «Simple Machines»